Installation fails: json.decoder.JSONDecodeError: Expecting ',' delimiter: line 7 column 3 (char 104)

[olippuner]

on windows-10

(base) PS D:\conda_wrk> jupyter nbextensions_configurator enable --user
Enabling: jupyter_nbextensions_configurator

• Writing config: C:\Users\olippuner.jupyter
  • Validating...
    jupyter_nbextensions_configurator 0.4.1 ok
    Enabling notebook nbextension nbextensions_configurator/config_menu/main...
    Traceback (most recent call last):
    File "c:\programdata\anaconda3\lib\runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
    File "c:\programdata\anaconda3\lib\runpy.py", line 87, in run_code
    exec(code, run_globals)
    File "C:\ProgramData\Anaconda3\Scripts\jupyter-nbextensions_configurator.EXE_main.py", line 7, in
    File "c:\programdata\anaconda3\lib\site-packages\jupyter_core\application.py", line 270, in launch_instance
    return super(JupyterApp, cls).launch_instance(argv=argv, **kwargs)
    File "c:\programdata\anaconda3\lib\site-packages\traitlets\config\application.py", line 664, in launch_instance
    app.start()
    File "c:\programdata\anaconda3\lib\site-packages\jupyter_nbextensions_configurator\application.py", line 117, in start
    super(JupyterNbextensionsConfiguratorApp, self).start()
    File "c:\programdata\anaconda3\lib\site-packages\jupyter_core\application.py", line 259, in start
    self.subapp.start()
    File "c:\programdata\anaconda3\lib\site-packages\jupyter_nbextensions_configurator\application.py", line 75, in start
    nbextensions.set_nbextension_state(
    File "c:\programdata\anaconda3\lib\site-packages\notebook\nbextensions.py", line 346, in set_nbextension_state
    cm.update(section, {"load_extensions": {require: state}})
    File "c:\programdata\anaconda3\lib\site-packages\notebook\config_manager.py", line 130, in update
    data = self.get(section_name)
    File "c:\programdata\anaconda3\lib\site-packages\notebook\config_manager.py", line 102, in get
    recursive_update(data, json.load(f))
    File "c:\programdata\anaconda3\lib\json_init.py", line 293, in load
    return loads(fp.read(),
    File "c:\programdata\anaconda3\lib\json_init.py", line 357, in loads
    return _default_decoder.decode(s)
    File "c:\programdata\anaconda3\lib\json\decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
    File "c:\programdata\anaconda3\lib\json\decoder.py", line 353, in raw_decode
    obj, end = self.scan_once(s, idx)
    json.decoder.JSONDecodeError: Expecting ',' delimiter: line 7 column 3 (char 104)
    (base) PS D:\OLI3\conda_wrk>

with
(base) PS D:\conda_wrk> conda info

 active environment : base
active env location : C:\ProgramData\Anaconda3
        shell level : 1
   user config file : C:\Users\olippuner\.condarc

populated config files : C:\Users\olippuner.condarc
conda version : 4.9.2
conda-build version : 3.18.11
python version : 3.8.3.final.0
virtual packages : __cuda=11.1=0
__win=0=0
__archspec=1=x86_64
base environment : C:\ProgramData\Anaconda3 (read only)
channel URLs : https://repo.anaconda.com/pkgs/main/win-64
https://repo.anaconda.com/pkgs/main/noarch
https://repo.anaconda.com/pkgs/r/win-64
https://repo.anaconda.com/pkgs/r/noarch
https://repo.anaconda.com/pkgs/msys2/win-64
https://repo.anaconda.com/pkgs/msys2/noarch
package cache : C:\ProgramData\Anaconda3\pkgs
C:\Users\olippuner.conda\pkgs
C:\Users\olippuner\AppData\Local\conda\conda\pkgs
envs directories : C:\Users\olippuner.conda\envs
C:\ProgramData\Anaconda3\envs
C:\Users\olippuner\AppData\Local\conda\conda\envs
platform : win-64
user-agent : conda/4.9.2 requests/2.24.0 CPython/3.8.3 Windows/10 Windows/10.0.19041
administrator : False
netrc file : None
offline mode : False